1. Field of the Invention
This invention relates to an electronic apparatus and an image display device in which at least two of many adjustment items are in close relation to each other.
2. Description of the Related Art
For suitably accomplishing a deflection adjustment of an image on a picture tube of an electronic apparatus or an image signal display device, for example, the picture tube of a television receiver, there are adjustment items such as horizontal and vertical deflection centers, and horizontal and vertical linearity distortions. It is to be noted that some of these adjustment items are in such close relation to each other so as to be affected by each other. For example, when vertical deflection size is changed, pin distortion and/or vertical linearity distortion occurs. Accordingly, adjustment for these distortions is necessary after changing the vertical deflection size.
In view of the above, the following technique has been developed as disclosed in Japanese Patent Provisional Publication No. 61-96872, upon paying attention to the fact that adjustment data (not to be adjusted) are in such a relation to another adjustment data (to be adjusted) as to obtain a suitable value relative to the latter adjustment data, under the effect of a predetermined relational expression or formula. This relational expression is stored in a ROM, and the adjustment data (not to be adjusted) are calculated using the relational expression when the adjustment data (to be adjusted) are changed. Thus, the adjustment data (not to be adjusted) are also changed along with the adjustment data (to be adjusted). According to this technique, changing only the adjustment data (to be adjusted) is sufficient to obtain a suitable image on the picture tube thereby making adjustments that may accompany the changing of the adjustment data (to be adjusted) unnecessary. Related techniques to the above are disclosed in U.S. Pat. Nos. 5,258,840 and 5,173,644.
However, drawbacks have been encountered in the above conventional technique. Because the above-mentioned relational expression is stored in a ROM, it is necessary to reproduce the ROM whenever replacement of parts, modification of a circuit, and/or addition of a new function is required. If no reproduction of the ROM is made, an optimum adjustment of the image on the picture tube cannot be achieved.